The Warriors go into final against Hull at Wembley as clear favourites to make it a record-extending 19th success but Offiah, who won the trophy four times with Wigan, is anticipating a close game.
"If you'd have asked me in June it would have been a definite 'yes' because they looked unbeatable at that time," Offiah said.
"But since then they've slipped a little bit. I don't go along with all this 'Wigan in crisis' talk but the game is not a forgone conclusion.
"Hull's young full-back Jamie Shaul seems to be an exceptional talent and his pace could be made for the wide open spaces of Wembley.
"But, if Wigan get parity in the pack, their outside backs can win the day for them."
Offiah, whose 90-metre solo try in the 1994 win over Leeds is widely recognised as the finest ever seen in a final, will be attending the game with his seven-year-old son Tyler, who will be wearing a Wigan shirt but will be unlikely to witness his favourite player.
"He's never been to a final but he's heard a lot about his dad," he said.
"He's in his first year of competitive rugby union but says one day he wants to play for Wigan.
"His favourite player is Dom Crosby but unfortunately it looks as though he won't be playing.
"I took him to a Wigan game at London Broncos and Dom took time out of the day to have a chat, which he has never forgotten. It's one of many endearing qualities in our game."
Offiah was speaking at a 2013 Rugby League World Cup event in Trafalgar Square to showcase rugby league in the build-up to the end-of season 14-team tournament.
"There's a lot going on," said Offiah, who was accompanied at the event by England coach Steve McNamara and captain Kevin Sinfield.
"I've seen plenty of Olympic volunteer jerseys here so people are coming out again to support the World Cup.
"There is an all-encompassing national feel to it and there is pressure on Steve McNamara and his team to perform."
Offiah likes England's chances but believes they would be improved had McNamara chosen Huddersfield's in-form captain Danny Brough, who has opted to once more play for Scotland after missing out on the England squad.
"I was a bit shocked to see Danny Brough not in the squad," Offiah said.
"I'm not here to second-guess the thoughts of the national coach but I don't think there are enough talented half-backs and, as soon as one goes down, we go to Australia to sign one.
"Hull did it (with Jacob Miller) and now Hull KR have done it (Kris Keating).
"But it's the coach's call and we've got to back the squad."